中文摘要：

为适应丘陵山区地形和不同农作物的农艺特点，提出一种具有平衡摇臂悬架和H型传动的可变地隙和轮距的动力平台，该平台采用无转向梯形的四轮全液压转向，转向方式为同侧两车轮采用对称角度的偏转转向，以减小转弯半径并实现同辙转向。采用遗传算法优化左、右转向油缸的位移关系，以实现阿克曼转向。为避免运动干涉，参照同轴距普通拖拉机的最小转弯半径确定车轮极限转角。当变地隙后车轮绕主销偏转，平台的轴距发生改变和变轮距后轮距发生改变后，可根据几何关系重新确定车轮在水平面内有效转角与转向油缸位移的关系，讨论了变地隙和变轮距满足阿克曼转向的条件。实验结果表明，设计的转向系结构和转向策略是合理的和可行的。

英文摘要：

A kind of Hilly power chassis with variable ground clearance and wheel track （VII-HPC） was designed to adapt to hilly terrain and agronomic characteristics of various types of crops. Hydraulic four wheel steering scheme without steering trapezoid has been proposed. To reduce turning radius and achieve same rut steering, the steering strategies are two ipsilateral wheels steering with a reverse and equal angle. The displacement relationship of right and left steering cylinder would be optimized by genetic algorithm to achieve Ackermann steering. The rotation of the steering wheel is not too large to avoid movement interference, which the minimum turning radius of the same wheelbase ordinary tractor was provided a reference. After change ground clearance, the wheel deflected around the kingpin. The relationship between the effective turning angle in the horizontal plane and the displacement of cylinder should be redefined according to the geometric relation. The conditions to meet the Ackermann steering need to be re-discussed because the wheelbase and track of the chassis would be altered after VII-HPC change ground clearance and the track. Experimental results show that the structure of steering system and steering strategy is reasonable and feasible.